Retinoblastoma is a disease in which malignant (cancer) cells form in the tissues of the retina.

The retina is the nerve tissue that lines the inside of the back of the eye. The retina senses light and sends images to the brain by way of the optic nerve.

Anatomy of the eye, showing the outside and inside of the eye including the sclera, cornea, iris, ciliary body, choroid, retina, vitreous humor, and optic nerve. The vitreous humor is a gel that fills the center of the eye.

Although retinoblastoma may occur at any age, it usually occurs in children younger than 5 years of age. The tumor may be in one eye or in both eyes. Retinoblastoma rarely spreads from the eye to nearby tissue or other parts of the body. Retinoblastoma is usually found in only one eye and can usually be cured.

Retinoblastoma is sometimes caused by a gene mutation passed from the parent to the child.

Retinoblastoma is sometimes inherited (passed from the parent to the child). Retinoblastoma that is caused by an inherited gene mutation is called hereditary retinoblastoma. It usually occurs at a younger age than retinoblastoma that is not inherited. Retinoblastoma that occurs in only one eye is usually not inherited. Retinoblastoma that occurs in both eyes is always inherited. When hereditary retinoblastoma first occurs in only one eye, there is a chance it will develop later in the other eye. After diagnosis of retinoblastoma in one eye, regular follow-up exams of the healthy eye should be done every 2 to 4 months for at least 28 months. After treatment for retinoblastoma is finished, it is important that follow-up exams continue until the child is 5 years of age.

Treatment for both types of retinoblastoma should include genetic counseling (a discussion with a trained professional about inherited diseases). Brothers and sisters of a child who has retinoblastoma should also have regular exams by an ophthalmologist (a doctor with special training in diseases of the eye) and genetic counseling about the risk of developing the cancer.

A child who has hereditary retinoblastoma is at risk for developing trilateral retinoblastoma and other cancers.

A child who has hereditary retinoblastoma is at risk for developing pineal tumors in the brain. This is called trilateral retinoblastoma. Regular follow-up exams using MRI (magnetic resonance imaging) or CT scans (computerized tomography) to check for this rare condition are important during treatment for retinoblastoma and should be continued until the child is 5 years of age. Hereditary retinoblastoma also increases the child's risk of developing other types of cancer in later years. Regular follow-up exams are important.

Possible signs of retinoblastoma include "white pupil" and eye pain or redness.

These and other symptoms may be caused by retinoblastoma. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:

• Pupil of the eye appears white instead of red when light shines into it. This may be seen in flash photographs of the child.
• Eyes appear to be looking in different directions.
• Pain or redness in the eye.